Two protocols - one for low bone mass, the 2nd for low bone mass and prior vertebral fracture - the same study design: 24 mos. of one of 2 doses of tiludronate vs. placebo (1/3 of patients in each group), with 12 mos of post treatment follow-up. All patients have calcium and vitamin D, bone density and spine X-rays performed to monitor bone mass and fracture incidence.